Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L17/00—Materials for surgical sutures or for ligaturing blood vessels ; Materials for prostheses or catheters
  • A61L17/14—Post-treatment to improve physical properties
  • A61L17/145—Coating
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M14/00—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials
  • D06M14/18—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation
  • D06M14/26—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation on to materials of synthetic origin
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M14/00—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials
  • D06M14/18—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation
  • D06M14/26—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation on to materials of synthetic origin
  • D06M14/28—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation on to materials of synthetic origin of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M14/00—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials
  • D06M14/18—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation
  • D06M14/26—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation on to materials of synthetic origin
  • D06M14/30—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials using wave energy or particle radiation on to materials of synthetic origin of macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M14/34—Polyamides
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/643—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/643—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain
  • D06M15/6436—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain containing amino groups
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/62—Plasma-deposition of organic layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2256/00—Wires or fibres

Definitions

• the present disclosure relates generally to coatings for filaments. More particularly, the present disclosure relates to silicone coatings for filaments or sutures formed by a plasma polymerization process.
• Synthetic sutures have been made from materials such as polypropylene, nylon, polyamide, polyethylene, polyesters such as polyethylene terephthalate, and segmented polyether-ester block copolymers.
• absorbable synthetic sutures have been prepared from synthetic polymers such as polymers containing glycolide, lactide, dioxanone, caprolactone, and/or trimethylene carbonate. Natural materials have also been used to make sutures. For example, silk has been used to make non-absorbable sutures. As another example, catgut sutures are absorbable sutures made from a natural material.
• Sutures intended for the repair of body tissues must meet certain requirements: they must be non-toxic, capable of being readily sterilized, they must have good tensile strength and have acceptable knot-tying and knot characteristics.
• the sutures should also be sufficiently durable from the point of view of fray resistance.
• Knot run down performance which reflects the ease of placement of a knot tied in a suture, is important in surgical procedures where it is necessary that a knot be tied in a suture when the knot is deep inside a surgical or natural opening. For instance, a dental surgeon may need to tie a knot inside a patient's mouth. An intravaginal hysterectomy requires suturing in restricted quarters.
• One technique frequently used is to tie a square knot that can be run down from an exterior location where the knot is first tied to lie against tissue with a desired degree of tightness.
• the knot is snugged down so that it is holding with a degree of firmness chosen by the surgeon for a particular situation and then additional throws, utilized to form additional knots, are tied down against the first throws of the square knot.
• the first throw is a double twist followed by a single throw to form a surgeons' knot, with additional throws to form additional square knots on top as needed.
• the ease with which a knot runs down the suture depends on a number of factors such as composition of the suture, braid structure of the suture, and the nature of the coating, if any, applied to the suture.
• the knot runs down the suture smoothly and easily.
• Knot security is the ability of the knot to hold-without slipping for an acceptable length of time.
• the characteristics of the suture material which allow a knot to hold securely are somewhat at odds with the characteristics of the suture material which provide satisfactory knot run down performance, since knot security requires that the suture grab itself while knot run down requires that the suture pass smoothly over itself. Accordingly, a balance of these two characteristics is normally required.
• Some synthetic sutures especially polypropylene monofilament sutures, have a tendency to fray as the suture passes over itself, e.g., when tying knots. While the limited amount of fraying exhibited by these sutures does not substantially hamper the performance of the suture, there remains room for improvement in the processing and the characteristics of such sutures.
• a suture it is also desirable for a suture to have low tissue drag, which is a measure of the force required to pull a suture through tissue. High drag forces result in chatter as the suture passes through tissue, make it more difficult for the surgeon to align tissue neatly, and increase the time to complete the closure being made with the suture.
• a wide variety of coatings have been applied to sutures of various types to improve one or more characteristics of the suture. See, for example, U.S. Pat. Nos. 3,187,752 ; 3,527,650 ; 3,942,523 ; 4,105,304 ; and 4,185,637 . These coatings include silicones. See U.S. Pat. No. 3,187,752 .
• Fibers or textile treatments which include organo silicon compounds have been described in, inter alia, U.S. Pat. Nos. 3,280,160 ; 3,418,354 ; 4,283,519 ; 4,359,545 ; 4,217,228 ; 4,784,665 ; 3,837,891 ; 4,207,071 ; 4,184,004 ; 4,578,116 ; 4,937,277 ; 4,617,340 ; and 4,624,676 .
• Siloxane-oxyalkylene copolymers have been described in U.S. Pat. Nos. 3,629,310 ; 3,755,399 ; 3,280,160 ; 3,541,127 ; and 4,699,967 .
• U.S. Pat. No. 5,383,903 discloses coating a surgical suture with a dimethylsiloxane-alkylene oxide copolymer lubricant.
• the present disclosure embraces a method for improving the handling characteristics of a suture by utilizing a plasma polymerization process to apply to the suture a coating comprising a siloxane polymer:
• Preferred coatings are formed by a plasma polymerization process whereby aliphatic hydrocyclosiloxane monomers are polymerized on the surface of the suture to form a siloxane coating on the suture.
• amine groups are introduced onto the polymer coating by co-polymerizing an organo-based monomer with the aliphatic hydrocyclosiloxane monomer or by carrying out a second plasma polymerization process for the introduction of the organo-based monomer.
• the amine groups on the polymer coating may then be reacted with carbonate polyoxyalkylenes to give polyoxyalkylene modified polymer coatings which enhance the handling characteristics of the coated sutures.
• Sutures treated in accordance with the present disclosure can be fabricated from a wide variety of natural and synthetic fibrous materials.
• Such materials include non-absorbable as well as partially and fully bioabsorbable (i.e., resorbable) natural and synthetic fiber-forming polymers.
• Non-absorbable materials which are suitable for fabricating sutures include silk, polyamides, polyesters such as polyethylene, polypropylene, cotton, linen, etc. Carbon fibers, steel fibers and other biologically acceptable inorganic fibrous materials can also be employed.
• Bio-absorbable sutures may be fabricated from natural collagenous material or synthetic resins including those derived from glycolic acid, glycolide, lactic acid, lactide, dioxanone, caprolactone, polycaprolactone, epsilon-caprolactone, trimethylene carbonate, etc., and various combinations of these and related monomers. Sutures prepared from resins of this type are known in the art. See, e.g., U.S. Pat. Nos. 3,297,033 ; 3,839,297 ; and 4,429,080 .
• the suture is made from a synthetic material.
• Suitable synthetic materials include, but are not limited to, polypropylene, nylon, polyamide, polyethylene, polyesters such as polyethylene terephthalate, segmented polyether-ester block copolymers and polyurethanes.
• Sutures treated in accordance with the present disclosure can have one or more filaments.
• the filaments may be braided, twisted, entangled, intertwined or arranged in some other multifilament configuration.
• a particularly useful braid structure for sutures is the spiroid braid structure described in U.S. Pat. Nos. 5,019,093 and 5,059,213 the disclosures of which are incorporated herein by reference.
• the sutures to be coated in accordance with the present disclosure are made of synthetic polymers.
• sutures treated in accordance with the present disclosure are subjected to a plasma polymerization process to form a polymer coating on at least a portion of the surface of at least one filament of the suture.
• plasma refers to a thermodynamically non-equilibrium gaseous complex, composed of electrons, ions, gas atoms, free radicals, and molecules in an excited state, known as the plasma state.
• Plasma may be generated in a process known as plasma discharge by a number of methods including combustion, flames, electric discharges, controlled nuclear reactions and shocks. The most obvious and commonly used is electric discharge. Radio frequency (“RF”) or microwave discharge are mainly used for polymerization reactions. For commercial RF generators, the frequency used in the process is dictated by the Federal Communications Commission and is set at 13.56 MHz.
• RF Radio frequency
• microwave discharge are mainly used for polymerization reactions.
• the frequency used in the process is dictated by the Federal Communications Commission and is set at 13.56 MHz.
• a plasma coating system with the same reactor geometry can be used if the W/FM formula is employed as a control indicator. If the system is controlled at a given pressure, increasing W and decreasing F will likely result in etching or ablation of the suture surface. If W is decreased and F is increased, the desired coating will most likely result.
• Modifications of the monomer flow rate and flow path are critical factors in avoiding two-phase coatings and obtaining the necessary high deposition rates of plasma polymerized coatings on suture surfaces.
• a high flow rate about 5 ⁇ mole/sec
• moderate R.F. power about 80 W
• low system pressure about 40 mTorr
• the monomers used to form the polymer coating are polymerized directly on the suture surface using plasma-state polymerization techniques generally known to those skilled in the art. See Yasuda, Plasma Polymerization, Academic Press Inc., New York (1985 ), incorporated herein by reference.
• the monomers are polymerized onto the suture surface by activating the monomer in a plasma state.
• the plasma state generates highly reactive species, which form the characteristically highly cross-linked and highly-branched, ultra-thin polymer coating, which is deposited on the suture surface as it moves through the area of the reactor having the most intense energy density, known as the plasma glow zone.
• a suitable organic monomer or a mixture of monomers having polymerizable unsaturated groups is introduced into the plasma glow zone of the reactor where it is fragmented and/or activated forming further excited species in addition to the complex mixture of the activated plasma gases.
• the excited species and fragments of the monomer recombine upon contact with the suture surface to form a largely undefined structure which contains a complex variety of different groups and chemical bonds and forms a highly crosslinked polymer coating on the suture surface.
• the polymeric deposit will include a variety of polar groups.
• the amount and relative position of polymer deposition on the sutures is influenced by at least three geometric factors: (1) location of the electrodes and distribution of charge; (2) monomer flow; and (3) suture position within the reactor relative to the glow region.
• (1) location of the electrodes and distribution of charge (2) monomer flow; and (3) suture position within the reactor relative to the glow region.
• the influence of the suture position is averaged over the length of the fibers.
• an electric discharge from an RF generator is applied to the "hot" electrodes of a plasma reactor.
• the selected monomers are introduced into the reactor and energized into a plasma, saturating the plasma glow zone with an abundance of energetic free radicals and lesser amounts of ions and free electrons produced by the monomers.
• the suture passes through or remains in the plasma glow zone, the surface of the suture is continually bombarded with free radicals, resulting in the formation of the polymer coating.
• the plasma chamber used for plasma polymerization has capacitively coupled plate-type electrodes.
• the sutures are exposed to monomers having a mass flow rate in the range from about 50 to about 100 standard cubic centimeters per minute (sccm), at an absolute pressure in the range from about 40 mTorr to about 70 mTorr.
• the exposure time ranges from about 45 seconds to about 9 minutes.
• the currently preferred exposure time is in the range from about 2 minutes to about 6 minutes.
• a radio frequency of 13.56 MHz in the range from about 25 watts to about 100 watts generates sufficient energy to activate the monomers.
• the monomer flow rate, power, chamber pressure, and exposure time may be outside the ranges of that set forth for the embodiment discussed above.
• the suture is subjected to both thermal and ultra-violet (UV) radiation.
• UV ultra-violet
• the heat generated can be removed by external fans constantly blowing onto the system.
• the heat generated by electrons, ions, or free radicals colliding with the suture surface is insignificant and will not effect the bulk mechanical properties of the suture. While the total energy released as heat or mechanical energy after impact is relatively small, the surface of the suture may become chemically active and unstable.
• the UV radiation generated from the plasma process can be harmful to polymeric sutures, such as polypropylene fibers.
• the UV radiation penetrates the surface of the suture, breaking the polymer chains at the surface: This is known as chain scission.
• the polymer chains may subsequently recombine. If polymer chain scission is the dominant process, the suture's mechanical strength will be weakened. If polymer chain recombination is the dominant process, the polymer units will form local cross-linked network structures, and the suture will lose ductility and become brittle. Accordingly, the intensity of the plasma glow zone, the substrate residence time in the plasma glow zone, and the substrate pulling tension need to be carefully controlled in order to achieve a proper balance between scission and recombination and minimize the plasma-induced damage to the suture.
• the plasma polymerization process not only forms a thin layer of polymerized siloxane on the surface of the suture but, as noted above, the thermal and UV radiation generated by the plasma process also activates the surface of the suture itself, permitting crosslinking of the siloxane coating with the polymeric suture material.
• the crosslinking of the siloxane coating with the suture surface Increase the mechanical strength of the suture material, which enhances the fray resistance of the suture without substantially changing its bulk properties.
• siloxane monomers are used in the plasma polymerization process to produce polymer coatings on the suture surfaces.
• One preferred polymer coating which can be deposited on the suture surface through the plasma state polymerization process of the present disclosure uses aliphatic hydrocyclosiloxane monomers of the general formula: where R is an aliphatic group and n is an integer from 2 to about 10, preferably 4 to 6.
• Preferred aliphatic hydrocyclosiloxane monomers include: 1,3,5,7-tetramethylcyclotetrasiloxane ("TMCTS”); 1,3,5,7,9-pentamethylhydrocyclopentasiloxane (“PMCTS”); 1,3,5,7,9,11-hexamethylhydrocyclohexasiloxane (“HMCHS”) and a mixture of 1,3,5,7,9-pentamethylcyclopentasiloxane and 1,3,5,6,9,11-hexamethylcyclohexasiloxane monomers (“XMCXS").
• TCTS 1,3,5,7-tetramethylcyclotetrasiloxane
• PMCTS 1,3,5,7,9-pentamethylhydrocyclopentasiloxane
• HMCHS 1,3,5,7,9,11-hexamethylhydrocyclohexasiloxane
• XMCXS 1,3,5,6,9,11-hex
• Radio frequency power greater than 5 W
• system pressure less than 300 mTorrs
• monomer flow rate greater than 1 ⁇ mole/sec
• the aliphatic hydrocyclosiloxane monomers noted above may be used to create a homogeneous coating on the suture surface.
• the aliphatic hydrocyclosiloxane monomers may be mixed with co-monomers to give polymer coatings having properties different from the properties of the homogenous coating. For example, by introducing reactive functionalizing monomers, or organo-based monomers, or fluorocarbon monomers together with the aliphatic hydrocyclosiloxane monomers in the plasma polymerization system, physical pore size and chemical affinity of the plasma copolymerized aliphatic hydrocyclosiloxane coating with selective monomers can be controlled.
• the polymer coatings may be produced by a plasma co-polymerization process of mixtures of the same aliphatic hydrocyclosiloxane monomers noted above with organo-based monomers that introduce amine groups onto the polymer coating and form amine grafted polymer coatings. It is more preferred to introduce these organo-based monomers onto the polymer coating in a second plasma grafting process which occurs after the plasma polymerization of the aliphatic hydrocyclosiloxane monomers.
• Suitable organo-based monomers include allylamine, N-trimethylsilylallylamine, unsaturated amines (both N-protected and N-unprotected), and cyclic aliphatic amines (both N-protected and N-unprotected).
• amine grafted polymer coatings refers to a polymer coating containing amine groups, which can be obtained either by co-polymerization of the organo-based monomer with the hydrocyclosiloxane monomer or by plasma grafting the organo-based monomer onto a previously formed siloxane polymer coating.
• these plasma treated sutures, possessing amine grafted polymer coatings are then reacted with carbonate-based polyoxyalkylene compounds to produce polyoxyalkylene modified polymer coatings.
• the carbonate-based polyalkylene oxide is of the general formula wherein R 1 is an N-benzotriazole group, an N-2-pyrrolidinone group, or a 2-oxypyrimidine group; R 2 , R 3 and R 4 are independently selected alkylene groups of about 2 to about 3 carbon atoms and may be the same or different; R 5 is selected from hydrogen, methyl, a carbonyloxy-N-benzotriazole group, a carbonyloxy-N-2-pyrrolidinone group, and a carbonyl-2-oxypyrimidine group; a is an integer from 1 to 1000 and each of b and c is an integer from 0 to 1000, where a+b+c is an integer from 3 to 1000.
• Suitable lower alkylene groups include those having about 2 to about
• R 2 , R 3 and R 4 is --(CH 2 CH 2 )-- or --CH 2 CH(CH 3 )-- or any combination thereof. More preferably R 2 , R 3 and R 4 are ethylene. According to a preferred aspect a, b, and c are selected so as to give a molecular weight for the PEG moiety of about 500 to about 20,000, more preferably from 3000 to 4000.
• Preferred polyoxyalkylene carbonates include, but are not limited to, polyoxyethylene bis-(2-hydroxypyrimidyl) carbonate, polyoxyethylene bis-(N-hydroxybenzotriazolyl) carbonate and polyoxyethylene bis-(N-hydroxy-2-pyrrolidinonyl) carbonate.
• polyoxyalkylene modified polymer coatings impart a good balance of knot run down and knot security characteristics, superior tissue drag characteristics, and improved fray resistance to sutures.
• these polyoxyalkylene modified polymer coatings possess a polyoxyalkylene tether capable attaching additional compounds, including lubricants or bioactive compounds, to the polymer coating.
• the resulting coating on the suture is between about 0.01 to about 10 percent by weight based upon the weight of the filament or filaments to which the coating is applied.
• the coating is applied in an amount of from about 0.05 to about 7.5 weight percent.
• the amount of coating is between about 0.1 and about 5 weight percent.
• the amount of coating applied to the suture may be adequate to coat all surfaces of the suture.
• the amount of coating applied will be that amount sufficient to improve the handling characteristics of the suture, regardless of whether the entire surface of the suture is coated.
• the term coating as used herein is intended to embrace both full and partial coatings.
• the amount of coating composition may be varied depending on the construction of the sutures, e.g., the number of filaments and tightness of braid or twist. In a preferred embodiment, the depth of crosslinking of the silicone coating with the surface of the suture is less than about 100 ⁇ .
• the coatings may optionally contain other materials including colorants, such as pigments or dyes, fillers or therapeutic agents, such as antibiotics, growth factors, antimicrobials, wound-healing agents, etc. Depending on the amount of coating present, these optional ingredients may constitute up to about 25 percent by weight of the coating.
• An important feature of the present invention is the creation of a continuous thin coating.
• the thickness of this coating can be determined gravimetrically, and the continuity of the coating can be determined by its permeability.
• These factors, along with the chemical composition of the coating (i.e., carbon, silicone, oxygen, nitrogen percentages), determined by ESCA (electron spectroscopy for chemical analysis) are some of the values which change as plasma parameters are modified.
• This experiment analyzed the fray resistance of synthetic sutures made of polypropylene (from United States Surgical, Norwalk, CT) treated in accordance with the present disclosure. Care was taken to minimize handling of the sutures, and whenever possible the sutures were handled with plastic forceps.
• the siloxane derivative, 1,3,5,7-tetramethylcyclo-terasiloxane was polymerized on the suture surface in a glow discharge plasma deposition lasting for varying amounts of time, forming a siloxane-coated suture.
• the TMCTS plasma was generated at 83 W, 55 mTorr, and a flow rate of 84 sccm. It was found that the application of the plasma coating for time periods ranging from 2 to 6 minutes formed polymer coatings that prevented the fraying of the polypropylene suture material.
• a second plasma polymerization process or plasma grafting process, was utilized to introduce amine groups onto the polymer coating.
• N-trimethylsilylallylamine (TMSAA) was plasma grafted to the siloxane-coated suture for 4 minutes at 65 mTorr, 35 W, and a flow rate of 42 sccm. This process introduced a protected amine to the siloxane coating, that was subsequently modified in the next step.
• Polyethylene oxide compound (PEOC) was used to prepare an activated-intermediate HPEOC, a bifunctional-crosslinker polyoxyethylene bis-(N-hydroxybenzotriazolyl) carbonate. HPEOC was then conjugated to the surface-bound primary amines during a 10 minute immersion in a solvent. During the conjugation, hydroxybenzotriazolyl carbonate was liberated and polyoxyethylene-(N-hydroxybenzotriazolyl) attached to the amine via a urethane bond.
• HPEOC Polyethylene oxide compound
• Sutures treated pursuant to this plasma polymerization process were subjected to a test to determine their fray resistance. There were 3 sets of sutures: 1-6 possessed a thin siloxane coating; 7-12 possessed a thick siloxane coating; and 13-18 possessed a thick coating of HPEOC over siloxane.
• the fray test passes the suture repeatedly over itself until the suture frays and eventually breaks (i.e., suture failure). The results, which are reported as number of cycles to suture failure, are presented below in Table 1.
• sutures coated in accordance with this disclosure have knot security equivalent to commercially available sutures, and thus exhibit an advantageous balance combination of good fray resistance and knot security.

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